[Sonar] The powerboats strike back

[Robb Harriss]

just so you know, the rings, and bow rings, fail all the time out on the 
Cape (all salt water). We have to check them all the time, what with 
tides, currents and serious weather trying to pull the boats off their 
moorings. Same thing in fresh water, but slower.

Shaina A Brown wrote:
> Yet another thanks to all who helped to save Tally Ho! from certain death. 
>
>    In terms of material failure, Im sure there was some wear and fatigue
> occuring on the bouy and pennant that contributed greatly to the failure.
> But as I talked about with Steve this morning, I think the larger problem
> is that the water is so diluted with fuel from powerboats that its
> basically like puting a chunk of metal into a solvent bath...and this
> speeds up the crack propagation and failure process ten fold. Any presence
> of tramp ions in a metal grain boundary is devastating to the strength of
> the metal. I bet that a simple pH test of Minnetonka water would scare most
> of us off from swimming ever again. Fortuneately, we can all learn from
> this mishap, and that Tally Ho! foundered into the safest place in the bay
> that it could have.  In terms of a solution...I guess we will all have to
> keep a closer eye and check on the corrosion and wear of each bouy
> frequently. And for all those times that the powerboaters couldnt zip
> through the channel at 50mph because of sailboats, the powerboats are
> striking back...see you all at the club. Thanks,
>
> Shaina 
>
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